Euro7: Will tyre wear become the biggest emissions problem?

According to estimates by the Federal Environment Agency, about 150,000 tonnes of tyre particles remain on the roads every year and from there get into the soil, rivers and lakes, and ultimately into drinking water. Tyre abrasion and the resulting release of microplastics and numerous pollutants could therefore become the biggest emission problem. A problem that even a switch to vehicles with more sustainable engines, such as electric cars, can do nothing about. In fact, tyre wear is even higher in these cases, as electric cars are heavier than their diesel and petrol counterparts - and therefore cause more friction on the road. In other words, electric cars probably pollute the environment less when it comes to exhaust, but are no longer considered entirely environmentally friendly when the pollutants left behind by tyre wear are also taken into account. 

This is precisely why the upcoming European exhaust emission standard, the so-called Euro7, will also take such emission factors seriously by providing emission standards that will also take tyre wear into account. For the tyre sector, this means a rethink in production and technology. 

Not all wheels perform similarly in abrasion tests. Cheaper products degrade more easily and bear more responsibility for pollution from microplastics and harmful tyre particles. What is certain, however, is that "electric cars have the unintended consequences of having higher tyre wear, unless we build better tyres" - explains Gunnlaugur Erlendsson, head of Enso Tyres. To this end, the company is working on the development of sustainable tyres for electric vehicles. And Michelin and Continental are also working on making their tyres more durable over the coming years. For example, Michelin has already reduced its wear by about five percent between 2015 and 2020. In the meantime, as tyre technology becomes more environmentally friendly, Euro7 should ensure the disappearance of the worst tyres and lead to 'a lot of particulates already being avoided' - according to Michelin expert Cyrille Roget. 

Any reduction achieved is welcomed by the environmental expert. But the demands are high in terms of the expected pollution potential of tyre-road particles. It is true that they are all not directly considered particulate matter - because only 1.3 % of them are smaller than 2.5 micrometres (PM 2.5) and 10 micrometres (PM 10). But they are not simple microplastics either. Some of the chemicals contained in tyre rubber are particularly harmful to the environment and health - such as the additive 6PPD, which becomes a toxic substance after oxidation. Most importantly, in contrast to engine emissions, which are gradually decreasing thanks to Euro standards, so-called non-exhaust emissions from tyres and brakes do not seem to be decreasing - influenced by the increase in vehicle weight due to transport electrification.  

However, the new emissions standard scheduled for 2025 is supposed to be the first step towards finally reducing them. On the one hand, Euro7 continues to deal with engine exhaust emissions - albeit not with much stricter regulations than the predecessor standard.  On the other hand, it is the first emission standard that takes into account the expected pollution from non-exhaust emissions when type-approving new vehicles. According to the new regulations, vehicles may only be driven with tyre models with which the car had previously passed homologation. This would be the only way for manufacturers to ensure that the limits for emissions of fine dust and microplastics are not exceeded on the road, as in laboratory tests. This would limit, if not completely prevent, the switch to other tyres. And accordingly avoid new tyres being marketed that do not meet Euro7 standards. However, to initiate a real change in the tyre industry, the rules should not only apply to new tyres - but also to the replacement market. Alternatively, the European Union could choose to regulate the approval of tyres based on abrasion independently of the vehicle, i.e. outside Euro 7. A threshold value for the maximum permitted abrasion in g/1000 km would then be set and all tyres on the market would thus be classified according to expected abrasion.  

The bottom line is that many questions remain unanswered in the context of regulations to reduce brake and rubber abrasion. No precise limits for tyre abrasion have yet been set for Euro7, for example. What is certain, however, is that once the standard comes into force, it will be the responsibility of manufacturers to produce tyres that comply with the new standards. Standards that can make life more difficult for companies in the industry and make the manufacturing process, including the final product, much more expensive. While some manufacturers, such as Michelin, welcome the introduction of a limit value to reduce pollution from tyre-road particulates, the number of those who see only drawbacks in the measures envisaged by the forthcoming emission standard is also growing. 

On the one hand, because in view of the ongoing conversion to e-mobility, the effort and benefit for the environment would be out of proportion - criticised the Association of European Automobile Manufacturers (ACEA) - and much more resources should be channelled into the research and production of greener forms of propulsion. Above all, however, because the new emissions standard could drive up prices substantially - for the car industry, as well as for the end consumers themselves. The European Commission estimates the additional costs per vehicle after the implementation of the Euro7 standard at an average of 80 to 180 euros. In its study, however, the consultancy Frontier Economics considers the development of Euro 7-compliant powertrains and tyres to be significantly more cost-intensive. For cars and vans with combustion engines, this would mean a price increase of between 1,862 and 2,629 euros per car - instead of between 184 and 446 euros per unit, as calculated by the EU. Diesel trucks and buses would cost as much as 11,707 euros more to produce, according to ACEA estimates, while the legislator expects additional costs of around 2,765 euros in the Euro7 forecast. In addition, there would be indirect costs that owners of Euro 7-compliant vehicles would have to bear - for example, due to the increased fuel consumption in operation caused by the more complicated exhaust gas purification system provided for by the emission standard.  

It is therefore no surprise that critical voices are becoming more and more vocal - while environmental experts complain that the future standard is too lax with the limits imposed. Not only in the ranks of the industrialists and the car lobby, but also among the politicians who lead the decision-making processes in Europe. Even among the EU member states, the European Commission's draft for stricter emission standards is increasingly meeting with resistance. Primarily a group of eight states around France and Italy oppose the planned Euro7 regulation and "reject any new exhaust emission standards for cars and vans". The reasons? Like the car industry, politicians fear the negative economic impact the emissions standard could have on the car market - including what the rising costs would mean for new car buyers. In addition, the eight EU countries criticise the allocation of essential resources to vehicle adaptation under the new regulation. It would make more sense - according to the joint discussion paper - to invest more in the promotion of low-emission technologies. After all, only these will make it possible to achieve the climate targets set after the planned phase-out of the internal combustion engine.  

In this sense, the future of the upcoming exhaust emission standard is unclear. It will not come into force until the EU Council of Ministers finally reaches an agreement on the Commission's proposal. However, the environmental impact of tyre wear already shows that even supposedly clean technologies like electromobility can harm the environment - and that doing without fossil fuels is not synonymous with being emission-free. Even though the Euro 7 standard is not without its weaknesses, it is a first step towards reducing such pollutants in the production and registration of future combustion vehicles. The car industry must continue to work on finding solutions for more abrasion-resistant tyres and greener engines. Just as policymakers must continue to take measures that take into account the industry's technical capabilities and climate targets at the same time - before tyre wear becomes the biggest emissions problem.